Overview

The Southern Alps Experiment (SALPEX) is a collaborative mountain meteorology research study in New Zealand. A World Wide Web page for SALPEX is being prepared, and a link to it will be provided from here once it is ready. SALPEX has two major goals: The first goal is aimed primarily at improvements to quantitative forecasts of extreme weather, of the distribution of rainfall and snow, and of the subsequent flow in the catchments fed by this precipitation. The second goal contributes to the international effort to improve the simulation of clouds and precipitation within global climate models and large-scale weather forecasting models.

In the first phase of SALPEX (1993-96) archived weather data, initial field campaigns, and mesoscale models are being used to explore mountain influences on South Island weather. Results from this first phase are being used to refine experimental plans and define hypotheses for testing during the main field work phase (1996-97). The final phase involves consolidating these experimental and modelling results into an improved quantitative understanding of mountain influences on New Zealand's weather.

Of particular interest within SALPEX are the influence of the mountains on:

SALPEX Field Campaigns

There have already been two modest SALPEX field campaigns, in November 1994 and in November 1995. In these field campaigns the routine New Zealand upper air and surface meteorological and hydrological observations were supplemented by temperature / moisture / wind soundings upwind and downwind of the mountains (using standard balloon sounding techniques), by 3 cm radar measurements on the upwind side of the mountains using a mobile radar capable of both vertically pointing and scanning operations, by additional raingauges including some very high time resolution gauges, and by disdrometers and an acoustic sounding technique for measuring drop size distributions. Atmospheric data from GMS and NOAA satellites has been archived for the field campaign periods, as well as information from a Doppler weather radar operated to the east of the mountains by the New Zealand Meteorological Service. Global analyses from the European Centre for Medium Range Weather Forecasting (ECMWF) are a further information source for the field campaigns.

A more extensive field campaign (SALPEX'96) is planned for October / November 1996. The Australian F27 research aircraft instrumented by the CSIRO Division of Atmospheric Research will be used to make cloud physics and environmental measurements, and to release dropsondes. An enhanced programme of supporting observations will be undertaken similar to those during the 1994 and 1995 campaigns. In addition, for SALPEX '96 we expect to have at least one more radar available, one or two more atmospheric sounding (balloon) systems, and posibly a wind profiler.

Relationship to the GEWEX Extra Tropical Layer Cloud Study

SALPEX has been identified as a " contributing field experiment" by Working Group 3 (extra-tropical layer clouds ) of the Global Cloud System Study (GCSS) within the Global Energy and Water Cycle Experiment (GEWEX). Working Group 3 of the GCSS is concerned with the parameterization of extra-tropical layer clouds within climate models and large-scale weather prediction models. (Here "parameterization" means a simplified mathematical representation of processes occuring on scales smaller than the grid-point separation used in the models).

Contacts for More Information

David Wratt, of the National Institute of Water and Atmospheric Research in Wellington New Zealand, is providing overall co-ordination of SALPEX. He is the primary contact for SALPEX. Brian Ryan of the CSIRO Division of Atmospheric Research in Melbourne has an overview of the proposed measurements from the CSIRO aircraft, and the links to the GEWEX GCCS studies. Stuart Bradley of Auckland University is familiar with the radar, high resolution rainfall, and acoustic sounder measurements.